The present invention relates to secondary electrical power distribution systems and more particularly to secondary electrical power distribution systems having network-controlled solid state power controllers.
In a conventional secondary electrical power distribution system (SEPDS), such as those used on aircraft, electric power is distributed to electrical loads through electromechanical relays in combination with circuit breakers. Due to increasing demands in avionic systems, there is a need for improvements in SEPDSs in the areas of reliability, size, weight and cost, which cannot always be met by electromechanical systems.
As a result, SEPDSs which use solid state power controller (SSPC) technology as an electric management center have been introduced. SSPCs offer a number of advantages over electromechanical relays and circuit breakers. In such systems, several SSPC channels are usually located on one circuit card assembly (CCA) and several of these CCAs are then installed in one line replaceable unit (LRU). The control of the SSPC channels is usually through a centralized gateway designated for the LRU via a main data bus. The local control circuitry on each CCA interfaces to the gateway via an internal data bus inside the LRU.
SEPDSs that utilize SSPC technology achieve some of the above-discussed needed improvements over electromechanical technology. Also, SSPC provides system intelligence, remote control, and convenient maintenance. However, there is still a need for improvements to SSPC-based SEPDS. Centralized control can introduce additional wiring and hardware, increase power consumption, and add to the material cost and to the system weight as compared to some electromechanical systems. The increased complexity of SSPC-based SEPDSs also can create reliability issues. Dependency among various SSPC channels means that the failure of one SSPC channel can affect other SSPC channels. There is also a need to reduce thermal dissipation in SSPC technology-based SEPDs, where, for example, several SSPC channels may be clustered in one CCA, and several CCAs, may be clustered in one envelope to share a common backplane, power supply and data bus. Also, SSPC-based SEPDs can not always be easily retrofitted into older systems that have electromechanical SEPDS.
As can be seen, there is a need for an SSPC-based SEPD which minimizes the hardware, power consumption, thermal dissipation, weight, size, and cost. There is a further need for an SSPC-based SEPD with improved reliability over existing systems. Still further there is a need for an SSPC-based SEPD that is easily retrofitted into an existing electro-mechanical SEPD system.